The invention relates to an electrical contact, in particular according to the precharacterising clause of claim 1.
European patent EP 0 762 551 describes a pin contact with a connecting part, a connector tongue, and a locking part. The locking part has a separate locking spring which may be inserted perpendicularly to the pin contact into the locking part. The connector tongue and the locking part are plugged into a mating counterpart and fixed in position therein by the locking spring.
Such pin contacts are conventionally stamped and formed from sheet metal blanks which provides good bending characteristics for cable clamping and which exhibits good electrical conductivity. Such metal is as a rule less usable as a spring material due to a lack of resilience and strength. A compromise material is not capable of fulfilling either requirement optimally.
In EP 0 762 551, a locking spring made from a different suitable material from the pin contact is used. The locking spring is connected with the pin contact using a two part format. Such two-part pin contacts are more expensive to produce than one-part pin contacts. This is because it is necessary to stamp and form two separate components from different materials and to assemble and clamp them together. Assembly and clamping is particularly costly. Moreover, clamping requires more complicated tools, which are not only expensive but also unreliable.
Mounting the locking spring in the direction perpendicular to the connector tongue, as in the European specification recited above, constitutes a considerable simplification relative to the method of sliding one of the two components axially into the other and clamping them together. However, even with the solution proposed in EP 0 762 551, it is still necessary to clamp the two components together to fix the locking spring in the locking part, which is correspondingly costly and time-consuming.
An object of the invention is to provide a pin contact made stamped and formed from a steel sheet with a separately produced locking spring which is economic to produce and mount.
This object is achieved by the features of claim 1. Because the locking spring has latching means, which fix the locking spring in position through insertion thereof into the locking part, the locking spring may be mounted merely by plugging it into the locking part. Clamping of the components is unnecessary, whereby complicated, time-consuming operations may be eliminated. Because the locking part has openings adapted for insertion and latching of the locking spring, the locking spring mounting process is simplified.
The locking spring may have guide surfaces which contribute to the simplification of locking spring mounting. Latching of the locking spring at its ends makes its connection with the locking part strong.
In order to facilitate mounting a first guide surface, preferably folded at right angles, may be arranged in the area of the rear end of the locking spring on each side thereof. In this way, the locking spring is guided at one end over the entire mounting path.
Handling of the locking spring is also improved. A latching means is provided at least on one of the two first guide surfaces. The latching means cooperate with the openings in the top of the locking part to limit rebound of the locking spring or prevents buckling thereof. The force required to tear the contact out of the chamber is thereby increased.
In various embodiments the latching means may take the form of a channel on the lower edge of a first guide surface or of a hook on a rear edge of a different first guide surface or of a perforation pocket or perforation tongue, which is arranged on the outside of a further first guide surface. The solution using the hook at the lateral edge of the different first guide surface is particularly favourable from a manufacturing perspective.
It is advantageous for the locking spring to have an obtuse-angled first folded portion and an obtuse-angled second folded portion in the area of its front end and for there to be arranged on each side of the obtuse-angled first folded portion a second guide surface folded inwards at right angles. The second guide surface has upper corners bent slightly outwards, which upper corners lie against an inner surface of the top or against an upper side of a side opening in the locking part after latching of the locking spring. The second guide surfaces simplify mounting of the locking spring at the other end thereof. The upper corners effect secure latching thereof in the locking part, wherein latching is reinforced by tensile loading of the locking spring.
An advantageous construction of the invention has an alternate locking spring which has a different obtuse-angled first folded portion, a right-angled second folded portion and an obtuse-angled third folded portion in the area of its different front end. A perforation tongue which is directed towards the connecting part is provided in the obtuse-angled third folded portion. The perforation tongue lies against the different inner surface of a different top of a different locking part after latching of the different locking spring. In this embodiment, the different end of the different locking spring may be produced in a particularly simple manner merely by three folded portions, since the outer edges thereof serve as guide surfaces. In this embodiment, tensile loading of the different locking spring reinforces latching.
In another embodiment, a further locking spring comprises a further obtuse-angled first folded portion, a further right-angled second folded portion and a further obtuse-angled third folded portion in the area of its further front end and in that a further second guide surface folded at right angles is arranged on each side of the further obtuse-angled first folded portion. A free end of the further obtuse-angled third folded portion lies against the further inner surface of a further top of a further locking part after latching-in of the further locking spring. The further second guide surfaces folded at right angles serve simultaneously to fix the locking spring in position in the longitudinal and transverse directions of the pin contact.
It may also be advantageous for the connector tongue to have two halves of arched cross section each with a tip, wherein the two halves adjoin at their edges and are at least pressed and/or welded together at their tips. In this way, the bending strength of the connector tongue is increased and the thickness thereof necessary for good electrical contact is achieved.